In the manufacture of wire rope, a plurality of wires is helically wound into strands that are, themselves, twisted with uniform pitch and direction around a core that may be fibrous or metallic. The individual strands, prior to being twisted into a rope, are preformed into a helical shape having a slightly smaller diameter than that assumed by the strand in the finished rope. In this way, the strands that comprise the rope are caused to more tightly encircle the core thereby enhancing the strength of the finished product.
In order to insure uniformity of product and of strand pitch it is necessary that each strand be preformed into a helix having prescribed dimensions. Thus, before the strands are twisted about the core, it is customary to measure each or a representative sample of strands in order to insure that they have been preformed within acceptable dimensional tolerance. Such measurement is conveniently obtained by simply measuring the height, or external diameter, of the helically wound strand; however, in the past such measurement has been obtained by simply visually gauging the helix height against a graduated scale. Obviously, the accuracy of visual measurement in this manner is highly suspect.
It is to the amelioration of the aforementioned problem, therefore, that the present invention is directed.